1. Technical Field
Aspects of the invention relate to sheet supplying device employed in an imaging device such as a printing device (e.g., a printer, a facsimile device, a multi function peripheral, etc.) or a scanning device for supplying sheets one by one in the imaging device.
2. Related Art
Conventionally, a sheet supplying device has been known and widely used. Such a sheet supplying device is typically configured such that a plurality of sheets are stacked on a sheet tray, and an upper surface of a leading end side portion of stacked sheets are press-contacted with a sheet feed roller. The sheet feed roller rotates to feed the recording sheet one by one in the imaging device. In such a conventional sheet supplying device, the upper surface of the stacked sheet should be press-contacted to the sheet feed roller regardless of the amount of the stacked sheets. In order to ensure the contact, the sheet tray is made movable toward and away from the sheet feed roller, and is biased toward the sheet feed roller using a spring or the like. In such a conventional configuration, room is required that allows the sheet tray, which has a substantially same size of the recording sheets, to move within a certain movable range. Obstacles have been encountered in providing desired room while downsizing the device.
To deal with the above drawback, Japanese Patent Provisional Publication No. HEI 10-101241 discloses a sheet supplying device, which is configured as follows. A stack of sheets is placed on a sheet tray such that the leading end portion of the stack of sheets is oriented toward a lower front side, and the leading end side of the stacked sheets is in contact with a support unit. The support unit in this publication is configured such that the recording sheets are movable toward the feed roller by means of their own weight. That is, stack of the recording sheets is moved toward the feed roller and is press-contacted thereto. With the configuration described in the publication, it is unnecessary to provide a room that allows the sheet tray to move. Thus, the entire device can be downsized.
According to the configuration disclosed in the publication No. HEI 10-101241, since the inclination angle of the supporting unit is fixed, when the amount of the stacked sheets is relatively large, a relatively large pressing force is applied to the feed roller by the weight of the sheets. In such a case, the plurality of sheets overlap when fed. On the other hand, if the amount of the stacked sheets is relatively small, the sheets are not press-contacted sufficiently because of their light weight, and the sheets may not be fed or fed properly by the feed roller.